1. Field of Invention
The present invention relates to a driving mechanism for a camera lens. More particularly, the present invention relates to a driving mechanism for an auto-focus camera lens.
2. Description of Related Art
Due to advances in photography, almost all modern camera equipment has the ability to focus such that an object can be clearly imaged in the camera no matter whether the object is near or far. Adjusting the lens makes the light irradiated into the camera aggregated at an optimum position, the so-called focus, and then an image can be clearly recorded by the camera.
Manual focus is used for tronal cameras; in other words, the position of a traditional camera lens is manually adjusted to a point determined by a user's naked eye. Although advanced users may obtain a better effect by manual focus, it may be too difficult for amateur users; therefore, the fully automatic camera has been presented to the public. A fully automatic camera can automatically determine a proper focal distance before an image is recorded; thus, the difficulty in using the camera and the possibility of a faulty focus can be reduced.
Generally, there are a processor and a lens driving mechanism in a camera for the simple auto-focus method. The processor has the ability to receive a light signal and determine the optimum lens position by some algorithms, and then the lens is shifted to that optimum position by the lens driving mechanism. An ordinary driving mechanism uses a typical rotary motor to shift a lens, and because the lens must shift straight back and forth, a transmission is needed between the rotary motor and the lens for transforming a rotary motion to a linear motion. Generally, the transmission is achieved by a cam and a gear wheel mechanism, making the transmission extensive and hard to apply in portable products, such as mobile phones.
Furthermore, according to the tendency for electronic products to be integrated, a camera may not only be a camera, but also a mobile phone or a PDA (personal digital assistant); thus, miniaturization of an electronic product is an important consideration. In the traditional lens driving method, both the rotary motor and also the transmission occupy a large volume. Consequently, the limitations of traditional cameras with respect to miniaturization are obvious.
According to the foregoing description, a lens driving mechanism with more accuracy, better control ability and less volume is certainly needed because modern standards of focusing accuracy and miniaturization of products are critical.